The present invention relates generally to metallized capacitors, and more specifically to a metallized capacitor having a roll of laminated dielectric films each being formed with a plurality of longitudinally spaced apart conductive segments.
Conventional metallized capacitors are broadly classified into roll and stack types. In the roll type, a dielectric film is vacuum evaporated with a continuous length of conductive layer and laminated with a similarly vacuum-evaporated dielectric film and the lamination is convolutely wound into a roll. Each dielectric film is provided with a marginal non-metallized area extending along one edge thereof which is opposite to the marginal area of the other film. On each end face of the roll is welded a conductive material so that it establishes an electrical connection with an associated one of the rolled conductive layers. In the stack type metallized capacitor, a plurality of metallized films, each having a non-metallized marginal area, is stacked one on each other so that each dielectric layer is sandwiched between conductive layers and marginal areas occur alternately on opposite edges of the stacked construction. A conductive material is welded to the opposite edges of the stacked construction to establish electrical connection to alternate conductive layers.
The roll type capacitor has an advantage in that it permits capacitors to be manufactured with each, but a disadvantage in that slight damage in a local area spreads to all parts of the capacitor and eventually leads to damage of the whole capacitor due to the physically integral construction of conductive layers. Thus, the roll type capacitor additionally requires a safety assurance device such as current fuse or temperature fuse to prevent total failure of the capacitor. On the other hand, due to the physical separation of the conductive layers, damage in the stack type can be confined to a local area. However, the disadvantage of the latter resides in the manufacture which compares unfavorably with the roll type.